This invention relates to measuring across textile structures.
It is known to measure properties of textile structures, and particularly fibre webs intended for making yarn or for non-woven textiles, by measuring the obscuring effect of the structure on a light source. A light source is disposed on one side of the web or other structure and a light sensor on the other side. This works quite well and is reasonably linear for light webs where the web fibres obscure up to about 75% of the direct illumination to the light sensor. At higher densities, however, most of the transmitted light is light that has passed through the fibres of the textile structure. The amount of light thus transmitted depends to a considerable extent upon the composition of the fibres, the filament cross-section, the nature and quantity of dye in or on the fibres, whether the fibres have optical brightening agents and like factors.
The present invention provides a method and apparatus for measuring across thick textile structures which is not subject to all the aforesaid disadvantages.